iPhone users can no longer downgrade from iOS 15.2
For all iPhone users who have upgraded or plan to upgrade their operating system to iOS 15.2, it appears that Apple has made it impossible to revert back to iOS 15.1—which the company has recently ceased signing, rendering it inaccessible to any devices.
The iOS 15.2 upgrade launched on December 13, and not only brought improved color to Apple's Safari browser on iPhone (and iPad), but also patched six separate vulnerabilities that were putting devices at a certain level of risk. As usual, users were encouraged to download it as soon as possible, in order to ensure that their phones were as safe as possible, and took advantage of the latest optimizations and system improvements.
iOS 15.1 also updated and improved SharePlay on FaceTime, the Covid-19 vaccination certificate in Apple's Wallet app (where it's compatible), the ProRes video format for the iPhone 13 Pro or iPhone 13 Pro Max, and many others.
However, it sometimes happens that some devices may experience bugs and crashes with a certain update, due to unforeseen software defects or incompatibilities. Usually, in that case, users may revert back to an older operating system version, until a yet newer one is released to solve those issues.
Another reason an iPhone user may want to downgrade their OS to an older version, is if they are interesting in jailbreaking their devices.
However, after today's turn of events, users who have downloaded iOS 15.2 as of last Monday, will no longer be able to revert back to an older OS version, and will be forced to stick with iOS 15.2—at least until a version iOS 15.3 or later is released.
As 9to5Mac reports, iOS 15.1 had already fallen out of reach for the iPhone 13 series that updated to iOS 15.1.1 back in November, a small update patching up a particular bug that encompassed the entire family of devices. But with iOS 15.2 out, the iOS 15.1 version is now completely inaccessible for iPhones and iPads across the board, and not jut the latest series.
Things that are NOT allowed: